This invention relates to lock and key sets which include reversible keys, and also to a dual cam, reversible key and to a method of making the key.
Over the years, various key configurations have been used for automotive lock applications. The traditional key configuration used for automotive applications has been the blade key. Notches are cut in an edge of the key blade for establishing the coding for the key. Other known types of blade keys have notches or grooves milled into the side of the key blade to provide the coding for the key. A further type of key, which is adapted for use with a rotary tumbler arrangement, has multiple milled surfaces formed on the end of a round shank.
In the traditional key and tumbler lock design, as the key is being inserted into or removed from the cylinder of the lock, a tumbler is cammed up in the lock when the tumbler engages an upward sloping surface of a notch in the key. However, such locks usually rely on a tumbler spring to hold the tumbler against the key when a downward sloping cam surface on the key passes by the tumbler. Problems can occur with this type of design when tumbler springs are broken, missing or malfunctioning or when the tumblers stick due to corrosion, ice or other contaminants that enter the lock. If, for any reason, the tumbler spring cannot provide sufficient force to move the tumbler, the lock becomes inoperative.
The problems associated with traditional key and tumbler designs have been alleviated to some extent by lock systems which include side-milled keys and rotary tumbler locks. The notches for side-milled keys are configured to cause the tumblers to be cammed up as well as down in the lock. Thus, lock systems employing side-milled key designs do not have to rely on a minimal force provided by a spring to return the lock tumblers to their locking position when the key is withdrawn, for example. The force available to shift the tumblers up and down is proportional to the force with which the key is inserted into or withdrawn from the lock. Consequently, the locks are much less susceptible to problems associated with tumbler sticking. Although side-milled keys and rotary tumbler locks offer improved performance over the traditional key and tumbler designs, high volume users, such as the automotive industry, have been reluctant to switch to lock systems which employ side-milled keys. This is partly because only a small percentage of lock producers, dealers and locksmiths have the capability of producing these alternate notch key designs, and some side-milled key configurations can be very costly to produce. In addition, some alternate key designs require very specialized equipment to produce and/or duplicate the keys.
A shortcoming of lock systems which include side-milled keys is that the locks typically require tumblers that have a small tab which rides in a track formed in the key shank for actuating the tumbler up and down as the key is inserted or removed. Such tabs are very vulnerable to damage and can be bent or broken off as the result of operating the lock, requiring repair or replacement of the lock.
It is, therefore, an object of the invention to provide a new and improved lock and key set.
Another object of the invention to provide a lock and key set which includes a dual cam, reversible key.
A further object of the invention to provide a dual cam, reversible key and a method of making the key.
Yet another object of the invention is to provide a dual cam, reversible key which is inexpensive to produce and which can be produced and/or duplicated using existing key manufacturing equipment.